Fixed parser bug, added option to output YAML 1.1

* Fixed a parser bug that got confused when looking for an implicit
   map key in a plain scalar that contains &, * or !
 * Added OutputYamlVersion to PresentationOptions

private/fastparse.nim

@@ -346,6 +346,7 @@ template handlePossibleMapStart(flow: bool = false,
         while p.lexer.buf[pos] notin {'\'', '\l', '\c', EndOfFile}:
           pos.inc()
       of '&', '*', '!':
+        if pos == p.lexer.bufpos or p.lexer.buf[p.lexer.bufpos] in {'\t', ' '}:
           pos.inc()
           while p.lexer.buf[pos] notin {' ', '\t', '\l', '\c', EndOfFile}:
             pos.inc()
@@ -776,8 +777,8 @@ template handleFlowPlainScalar() {.dirty.} =
 template ensureCorrectIndentation() {.dirty.} =
   if level.indentation != indentation:
     startToken()
-    parserError("Invalid indentation (expected indentation of " &
-                $level.indentation & ")")
+    parserError("Invalid indentation: " & $indentation &
+                " (expected indentation of " & $level.indentation & ")")
 
 template tagHandle(lexer: var BaseLexer, content: var string,
                    shorthandEnd: var int) =
@@ -868,7 +869,8 @@ template blockScalar(lexer: BaseLexer, content: var string,
       blockIndent = int(lexer.buf[lexer.bufpos]) - int('\x30')
       detectedIndent = true
     of spaceOrLineEnd: break
-    else: lexerError(lexer, "Illegal character in block scalar header")
+    else: lexerError(lexer, "Illegal character in block scalar header: '" &
+                     lexer.buf[lexer.bufpos] & "'")
   lexer.lineEnding()
   case lexer.buf[lexer.bufpos]
   of '\l': lexer.bufpos = lexer.handleLF(lexer.bufpos)

private/presenter.nim

@@ -15,10 +15,12 @@ type
         sLiteral, sFolded, sPlain, sDoubleQuoted
 
 proc defineOptions*(style: PresentationStyle = psDefault,
-                    indentationStep: int = 2, newlines:
-                    NewLineStyle = nlOSDefault): PresentationOptions =
-    result = PresentationOptions(style: style, indentationStep: indentationStep,
-                                 newlines: newlines)
+                    indentationStep: int = 2,
+                    newlines: NewLineStyle = nlOSDefault,
+                    outputVersion: OutputYamlVersion = ov1_2):
+        PresentationOptions =
+    PresentationOptions(style: style, indentationStep: indentationStep,
+                        newlines: newlines, outputVersion: outputVersion)
 
 proc inspect(scalar: string, indentation: int,
              words, lines: var seq[tuple[start, finish: int]]):
@@ -30,7 +32,8 @@ proc inspect(scalar: string, indentation: int,
         curWord, curLine: tuple[start, finish: int]
         canUseFolded = true
         canUseLiteral = true
-        canUsePlain = scalar.len > 0 and scalar[0] notin {'@', '`'}
+        canUsePlain = scalar.len > 0 and
+                scalar[0] notin {'@', '`', '|', '>', '&', '*', '!', ' ', '\t'}
     for i, c in scalar:
         case c
         of ' ':
@@ -338,7 +341,10 @@ proc present*(s: var YamlStream, target: Stream, tagLib: TagLibrary,
             if options.style != psJson:
                 # TODO: tag directives
                 try:
-                    target.write("%YAML 1.2" & newline)
+                    case options.outputVersion
+                    of ov1_2: target.write("%YAML 1.2" & newline)
+                    of ov1_1: target.write("%YAML 1.1" & newLine)
+                    of ovNone: discard
                     if tagLib.secondaryPrefix != yamlTagRepositoryPrefix:
                         target.write("%TAG !! " &
                                 tagLib.secondaryPrefix & newline)

yaml.nim

@@ -211,11 +211,23 @@ type
         ##   sequence (CRLF on Windows, LF everywhere else).
         nlLF, nlCRLF, nlOSDefault
     
+    OutputYamlVersion* = enum
+        ## Specify which YAML version number the presenter shall emit. The
+        ## presenter will always emit content that is valid YAML 1.1, but by
+        ## default will write a directive ``%YAML 1.2``. For compatibility with
+        ## other YAML implementations, it is possible to change this here.
+        ##
+        ## It is also possible to specify that the presenter shall not emit any
+        ## YAML version. The generated content is then guaranteed to be valid
+        ## YAML 1.1 and 1.2 (but not 1.0 or any newer YAML version).
+        ov1_2, ov1_1, ovNone
+            
     PresentationOptions* = object
         ## Options for generating a YAML character stream
         style*: PresentationStyle
         indentationStep*: int
         newlines*: NewLineStyle
+        outputVersion*: OutputYamlVersion
     
     RefNodeData = object
         p: pointer
@@ -512,9 +524,10 @@ proc parse*(p: YamlParser, s: Stream): YamlStream {.raises: [].}
     ## Parse the given stream as YAML character stream. 
 
 proc defineOptions*(style: PresentationStyle = psDefault,
-                    indentationStep: int = 2, newlines:
-                    NewLineStyle = nlOSDefault): PresentationOptions
-            {.raises: [].}
+                    indentationStep: int = 2,
+                    newlines: NewLineStyle = nlOSDefault,
+                    outputVersion: OutputYamlVersion = ov1_2):
+        PresentationOptions {.raises: [].}
     ## Define a set of options for presentation. Convenience proc that requires
     ## you to only set those values that should not equal the default.